This invention relates generally to an improved means of setting the alarm time for an electronic alarm timepiece.
Electronic alarm timepieces are known which include a piezoelectric transducer and alarm driving circuit for causing the transducer to produce an audible sound after an elapsed time has been measured by the timekeeping circuitry of the electronic timepiece, or after the alarm set time coincides with the actual time. When the timepiece has a digital display, there is normally a pushbutton which can be actuated to place the display in alarm mode and easily set the desired time for the alarm to sound. However, in a quartz analog watch having hands driven by a stepping motor, indicating and setting the desired time for the alarm to go off is more difficult. Several schemes have been devised for temporarily moving the hands to indicate the alarm set time. These are always complicated, because some means must be provided to return the hands to show the correct time again after they have been moved, without losing track of the correct time.
U.S. Pat. No. 4,223,523 - Kamijo discloses an electronic analog wristwatch with an alarm which is set by rapidly, electromechanically driving the watch hands forward to the desired alarm time, slowly advancing the hands electromechanically to the exact alarm setting, and then rapidly returning by electromechanically driving the hands to the actual present time. The number of pulses required for hand return are counted and used to actuate an alarm when a coincidence detector indicates that a number of real time pulses after return of the hands equals the count stored in memory.
U.S. Pat. No. 4,358,840 - Ono et al., discloses an electronic alarm timepiece with circuitry for controlling the drive of the hands by a reversible stepping motor to selectively position the hands at a desired alarm time and display time settings. A time difference counter is implemented for counting and storing the value corresponding to the difference in time between the alarm time and the present time. Another counter is used to activate the alarm when its content becomes zero.
U.S. Pat. No. 4,419,019 - Nishimura discloses a means for rapidly rotating the timepiece hands to indicate an alarm time, and further includes means for more precisely setting the alarm time by rotating the crown to generate drive pulses for advancing the timepiece hands in steps of one minute in the alarm time setting mode. The crown rotation actuates switches which provide setting pulses as well as providing audible click sounds to the operator.
U.S. Pat. No. 4,470,707 - Chambon et al., assigned to the present assignee, discloses an arrangement for setting the alarm time using the minute and second hand to indicate the alarm time in hours and minutes, by counting and storing the number of pulses produced when rotating the hands from a given reference position to the alarm set position.
All of the foregoing arrangements require changing the position of the timekeeping hands and therefore require complicated systems to return the hands to their former position, while compensating for time elapsed during setting.
Rotatable rings mounted on the watch bezel for indicating elapsed time through indicia which are compared to the hands of the watch are well-known, as illustrated in U.S. Pat. No. 3,553,958 - Grohoski, assigned to applicants' assignee. It is also well-known that a piezoelectric transducer used to produce an alarm sound or beeping sound in an electronic wristwatch can also act as a microphone to produce electronic pulses upon receipt of acoustic energy or sound impulses. An example of use of this principle to set a digital watch is illustrated in U.S. Pat. No. 4,477,194 - Michel et al. In this watch, ribbed zones on the watch bezel are scratched or rubbed to produce noise pulses or spikes detected by the electronic circuit to enable watch setting functions.
There is a great need for a simple means to set an electronic analog alarm timepiece without disturbing the setting of the timekeeping hands.
Accordingly, one object of the present invention is to provide an improved means for setting an alarm in an electronic alarm timepiece.
Another object of the present invention is to provide an improved means for indicating elapsed time for a timer.